The present invention relates to fiber of a polyadipamide polymer such as a yarn of nylon 66 or nylon 46 polymer and processes for making such fiber.
Polyadipamides such as nylon 66 and nylon 46 are desirable for use in the manufacture of high strength yarns for industrial use. Increasing the relative viscosity (RV) of polyadipamides enables tenacity to be increased to higher levels than are customarily obtainable with lower RV polymer. However, the high viscosity polymer has been found to limit production rates due to the high pressure drops which occur as the molten polymer is pumped to the spinneret. In addition, the use of high RV polymer 66 sometimes results in high yarn break levels and low yarn strength which limit yield of the resulting yarn.
Succinic acid is typically present at low levels in polyadipamides since it is present as an impurity in the adipic acid used to make the polymer. Typical levels of succinic acid in the polymer are in the range of 10 to about 25 parts-per-million (ppm) by weight.